LOS ANGELES (AP)  An Uzbek refugee imprisoned for plotting to kill U.S. military personnel or civilians has pleaded guilty to trying to kill a California federal prison warden.

Fazliddin Kurbanov pleaded guilty Tuesday in U.S. District Court in Los Angeles to attempted murder of a federal officer.

Federal prosecutors say the 34-year-old Kurbanov admitted fashioning a knife and trying to slit the throat of Calvin Johnson at the Federal Correctional Institute at Victorville in 2016.

Kurbanov faces at least 15 years added to the 25-year term he is serving for providing material support to a foreign terrorist organization.

Prosecutors say the Russian-speaking truck driver had downloaded jihadist and martyrdom videos from a terrorist website and communicated with the Islamic Movement of Uzbekistan, a terrorist organization.